686 research outputs found
Prototype of a low-cost 3D breast ultrasound imaging system
This work describes a setup of the new
acquisition system for 3D ultrasound images (i.e. B-mode) for
breast tomography. Since premature and precise breast
lesions diagnoses turn out in treatment more efficient and save
lives, we are looking for a more precise, less painful exams and
dose reduction for the patient. Therefore, a low cost scanner
mechanism was built aiming to accommodate breasts under
water while patient is laid down on a bed in which a robotic
arm guides the ultrasound probe to acquire 2D images. Then
3D image is reconstructed using the 2D images due to render
the mammary volume searching for lesions. The low cost
scanner was built using a regular ultrasound machine, linear
probe and major controls made by an Arduino Uno. We
compared the acquired phantom images with gold standard
images for mammary tissues diagnostics, i.e. Computerized
Tomography and Magnetic Resonance Images. This study
was evaluated using a paraffin-gel and mineral oil control
phantom. Results show that the provided module is convicting
enough to be used in local hospital as the next step of this
study
The sexuality of HIV-positive adolescents: rights and challenges for healthcare
Sexualidade e saĂșde reprodutiva configuram questĂ”es relevantes para o cuidado integral Ă saĂșde de pessoas vivendo com HIV. PolĂticas pĂșblicas e serviços de saĂșde, entretanto, tĂȘm dedicado insuficiente atenção ao assunto. O objetivo deste trabalho Ă© compreender como adolescentes e jovens soropositivos lidam com suas experiĂȘncias sexuais e projetos de namoro, desejo de constituir famĂlia e de ter filhos. O estudo qualitativo entrevistou em profundidade 21 adolescentes vivendo com HIV (por transmissĂŁo vertical, sexual ou sanguĂnea) e 13 cuidadores de crianças e jovens, vivendo em SĂŁo Paulo e em Santos, Brasil. As narrativas descrevem como aprenderam a lidar com a sexualidade e a ansiedade da revelação do diagnĂłstico nesse contexto. Destacam-se nas narrativas o despreparo, a desinformação sobre prevenção e a falta de apoio para lidar com a situação, assim como o estigma e a discriminação que atravessa grande parte das dificuldades relatadas. O artigo discute criticamente alguns dos desafios postos para uma adequada atenção Ă questĂŁo no Brasil, especialmente a consideração de jovens soropositivos como sujeitos de direitos sexuais, sugerindo diretrizes para a incorporação desta temĂĄtica a um cuidado integral e humanizado de crianças e jovens vivendo com HIV.Sexuality and reproductive healthcare represent relevant issues for comprehensive care of HIV-positive adolescents. However, public policies and health services give this issue insufficient attention. The scope of this article is to assess how HIV-positive young people and teenagers cope with their sexuality, dating and the urge to have children and start a family. In a qualitative study, in-depth interviews were staged with 21 HIV-positive (contracted by vertical, sexual or intravenous transmission) teenagers and 13 caregivers of children and youths living in Sao Paulo and Santos. The interviews revealed the different ways teenagers cope with their sexuality and with the anxiety of HIV disclosure in this context. Lack of information about HIV prevention, lack of support and skills to cope with their sexuality were revealed in the reports. Furthermore, stigma and discrimination were the most frequently reported difficulties. The main challenges to be faced in Brazil in regard to this issue are discussed, especially the need to consider HIV-positive youth as entitled to sexual rights. Recommendations are also made for incorporating the issue into a humanized and comprehensive care approach for HIV-positive children and young people
Search for sterile neutrino mixing in the MINOS long-baseline experiment
A search for depletion of the combined flux of active neutrino species over a 735 km baseline is reported using neutral-current interaction data recorded by the MINOS detectors in the NuMI neutrino beam. Such a depletion is not expected according to conventional interpretations of neutrino oscillation data involving the three known neutrino flavors. A depletion would be a signature of oscillations or decay to postulated noninteracting sterile neutrinos, scenarios not ruled out by existing data. From an exposure of 3.18Ă1020 protons on target in which neutrinos of energies between ~500¿¿MeV and 120 GeV are produced predominantly as ¿”, the visible energy spectrum of candidate neutral-current reactions in the MINOS far detector is reconstructed. Comparison of this spectrum to that inferred from a similarly selected near-detector sample shows that of the portion of the ¿” flux observed to disappear in charged-current interaction data, the fraction that could be converting to a sterile state is less than 52% at 90% confidence level (C.L.). The hypothesis that active neutrinos mix with a single sterile neutrino via oscillations is tested by fitting the data to various models. In the particular four-neutrino models considered, the mixing angles Âż24 and Âż34 are constrained to be less than 11° and 56° at 90% C.L., respectively. The possibility that active neutrinos may decay to sterile neutrinos is also investigated. Pure neutrino decay without oscillations is ruled out at 5.4 standard deviations. For the scenario in which active neutrinos decay into sterile states concurrently with neutrino oscillations, a lower limit is established for the neutrino decay lifetime t3/m3>2.1Ă10-12¿¿s/eV at 90% C.L
Neutrino Masses and Mixing: Evidence and Implications
Measurements of various features of the fluxes of atmospheric and solar
neutrinos have provided evidence for neutrino oscillations and therefore for
neutrino masses and mixing. We review the phenomenology of neutrino
oscillations in vacuum and in matter. We present the existing evidence from
solar and atmospheric neutrinos as well as the results from laboratory
searches, including the final status of the LSND experiment. We describe the
theoretical inputs that are used to interpret the experimental results in terms
of neutrino oscillations. We derive the allowed ranges for the mass and mixing
parameters in three frameworks: First, each set of observations is analyzed
separately in a two-neutrino framework; Second, the data from solar and
atmospheric neutrinos are analyzed in a three active neutrino framework; Third,
the LSND results are added, and the status of accommodating all three signals
in the framework of three active and one sterile light neutrinos is presented.
We review the theoretical implications of these results: the existence of new
physics, the estimate of the scale of this new physics and the lessons for
grand unified theories, for supersymmetric models with R-parity violation, for
models of extra dimensions and singlet fermions in the bulk, and for flavor
models.Comment: Added note on the effects of KamLAND results. Two new figure
Impacts of climate change on plant diseases â opinions and trends
There has been a remarkable scientific output on the topic of how climate change is likely to affect plant diseases in the coming decades. This review addresses the need for review of this burgeoning literature by summarizing opinions of previous reviews and trends in recent studies on the impacts of climate change on plant health. Sudden Oak Death is used as an introductory case study: Californian forests could become even more susceptible to this emerging plant disease, if spring precipitations will be accompanied by warmer temperatures, although climate shifts may also affect the current synchronicity between host cambium activity and pathogen colonization rate. A summary of observed and predicted climate changes, as well as of direct effects of climate change on pathosystems, is provided. Prediction and management of climate change effects on plant health are complicated by indirect effects and the interactions with global change drivers. Uncertainty in models of plant disease development under climate change calls for a diversity of management strategies, from more participatory approaches to interdisciplinary science. Involvement of stakeholders and scientists from outside plant pathology shows the importance of trade-offs, for example in the land-sharing vs. sparing debate. Further research is needed on climate change and plant health in mountain, boreal, Mediterranean and tropical regions, with multiple climate change factors and scenarios (including our responses to it, e.g. the assisted migration of plants), in relation to endophytes, viruses and mycorrhiza, using long-term and large-scale datasets and considering various plant disease control methods
Modeling the Subsurface Structure of Sunspots
While sunspots are easily observed at the solar surface, determining their
subsurface structure is not trivial. There are two main hypotheses for the
subsurface structure of sunspots: the monolithic model and the cluster model.
Local helioseismology is the only means by which we can investigate
subphotospheric structure. However, as current linear inversion techniques do
not yet allow helioseismology to probe the internal structure with sufficient
confidence to distinguish between the monolith and cluster models, the
development of physically realistic sunspot models are a priority for
helioseismologists. This is because they are not only important indicators of
the variety of physical effects that may influence helioseismic inferences in
active regions, but they also enable detailed assessments of the validity of
helioseismic interpretations through numerical forward modeling. In this paper,
we provide a critical review of the existing sunspot models and an overview of
numerical methods employed to model wave propagation through model sunspots. We
then carry out an helioseismic analysis of the sunspot in Active Region 9787
and address the serious inconsistencies uncovered by
\citeauthor{gizonetal2009}~(\citeyear{gizonetal2009,gizonetal2009a}). We find
that this sunspot is most probably associated with a shallow, positive
wave-speed perturbation (unlike the traditional two-layer model) and that
travel-time measurements are consistent with a horizontal outflow in the
surrounding moat.Comment: 73 pages, 19 figures, accepted by Solar Physic
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